Silicon-based heat dissipation device for heat-generating devices

ABSTRACT

Embodiments of a silicon-based heat dissipation device and a chip module assembly utilizing the silicon-based heat dissipation device are described. In one aspect, the chip module assembly includes a chip module and a primary heat dissipation module. The chip module includes a board and at least one heat-generating device. The board includes a first primary side and a second primary side opposite the first primary side. The at least one heat-generating device is disposed on the first primary side of the board. The primary heat dissipation module includes at least one silicon-based heat dissipation device disposed on the at least one heat-generating device.

CROSS REFERENCE TO RELATED PATENT APPLICATION

This application claims the priority benefit and is a non-provisional of U.S. Patent Application No. 61/807,655, filed 2 Apr. 2013 and entitled “Silicon-Based Heat Dissipation Device For Heat-Generating Devices,” which is herein incorporated by reference.

TECHNICAL FIELD

The present disclosure generally relates to the field of transfer of thermal energy and, more particularly, removal of thermal energy from electrically-driven devices.

BACKGROUND

There are many applications, ranging from consumer electronics to telecommunications and the like, in which electrically-driven devices (e.g., electronic devices such as semiconductor-based integrated circuits) capable of performing various tasks are packed in close proximity in a small form factor to serve various needs. Such electrically-driven devices may include, for example, driver circuits, microprocessors, graphics processors, memory chips, global positioning system (GPS) chips, communications chips, laser diodes including edge-emitting lasers and vertical-cavity surface-emitting lasers (VCSELs), light-emitting diodes (LEDs), photodiodes, sensors, etc. Many of such electrically-driven devices inevitably generate thermal energy, or heat, in operation and thus are heat sources during operation as well as for a period of time after power off. As the number and complexity of the functionalities performed by such electrically-driven devices continue to increase and as the distance between electrically-driven devices in the small form factor continues to decrease, heat generated by such electrically-driven devices, as heat sources, present technical challenges that need to be addressed.

For one thing, performance, useful lifespan, or both, of an electrically-driven device may be significantly impacted if the heat generated by the device is not adequately dissipated or otherwise removed from the device. Moreover, in many present-day applications, given the close proximity between two or more electrically-driven devices on the same substrate, e.g., printed circuit board (PCB), a phenomenon of thermal coupling between the two or more devices in close proximity may occur and result in the heat generated by one of the devices being transferred to one or more adjacent devices. When thermal coupling occurs, at least a portion of the heat generated by a first electrically-driven devices is transferred to a second electrically-driven device in close proximity due to temperature gradient, such that the temperature of the second electrically-driven device rises to a point higher than it would be when no heat is transferred from the first electrically-driven device to the second electrically-driven device. More specifically, when thermal coupling occurs and when no adequate heat transfer mechanism exists, heat generated by electrically-driven devices in close proximity may detrimentally deteriorate the performance and useful lifespan of some or all of the affected devices. As electrically-driven devices generate heat, they are referred to as heat-generating devices hereinafter.

Metal heat sinks or radiators, based on copper or aluminum for example, have been a dominant heat sink choice for electronics or photonics applications. As the form factor of electronic components (e.g., integrated circuits or IC) gets smaller it is impractical to build a small metal heat sink with a large surface area heat sink. Other problems associated with metal heat sinks include, for example, difficulty in precision alignment in mounting laser diode bars, VCSELs, LEDs or chips in laser diode/VCSEL/LED cooling applications, issues with overall compactness of the package, corrosion of the metallic material in water-cooled applications, difficulty in manufacturing, high-precision fabrication, electrical isolation, etc. Yet, increasing demand for higher power density in small form factor motivates the production of a compact cooling package with fewer or none of the aforementioned issues. Moreover, conventional packages typically use wire bonding to provide electrical power to the electrically-driven device(s) being cooled, but wire bonding may add cost and complexity in manufacturing and may be prone to defects in addition to occupying space unnecessarily.

SUMMARY

Various embodiments disclosed herein pertain to a technique, design, scheme, device and mechanism for isolation of thermal ground for multiple heat-generating devices on a substrate.

In one aspect, a device may include a silicon-based heat dissipation device. The silicon-based heat dissipation device may include a base portion and a protrusion portion. The base portion may have a first primary side and a second primary side opposite the first primary side. The protrusion portion may be on the first primary side of the base portion and may protrude therefrom. The second primary side of the base portion may be configured to have one or more heat-generating devices embedded therein or physically coupled thereto such that at least a portion of heat generated by the one or more heat-generating devices is dissipated to the silicon-based heat dissipation device by conduction.

In at least one embodiment, the base portion may include a slit opening that communicatively connects the first primary side and the second primary side of the base portion.

In at least one embodiment, when each of more than one heat-generating devices is embedded in or physically coupled to the base portion, at least a first heat-generating device of the more than one heat-generating devices may be on a first side of the slit opening and at least a second heat-generating device of the more than one heat-generating devices may be on a second side of the slit opening opposite the first side of the slit opening such that the slit opening severs a direct-line thermal coupling path via conduction through the base portion between the first and the second heat-generating devices.

In at least one embodiment, the slit opening may include an L-shaped slit opening.

In at least one embodiment, the protrusion portion of the silicon-based heat dissipation device may include a plurality of fins.

In at least one embodiment, the plurality of fins may include a plurality of straight fins.

In at least one embodiment, a ratio of a height of the fins, measured from the first primary side of the base portion in a direction perpendicular to the first primary side, to a thickness of each of the fins, measured across a respective one of the fins in a direction parallel to the first primary side of the base portion, may be greater than 5:1.

In at least one embodiment, a ratio of a height of the fins, measured from the first primary side of the base portion in a direction perpendicular to the first primary side, to a thickness of the base portion, measured across the base portion in a direction parallel to the first primary side of the base portion, may be greater than 5:1.

In at least one embodiment, a spacing between every two fins of the fins, measured between respective two fins of the fins in a direction parallel to the first primary side of the base portion, may be greater than or equal to a thickness of each of the fins, measured across a respective one of the fins in the direction parallel to the first primary side of the base portion.

In at least one embodiment, the plurality of fins may include a plurality of pin fins.

In at least one embodiment, the plurality of fins may include a plurality of flared fins.

In at least one embodiment, the device may further include one or more integrated circuits embedded in the second primary side of the base portion or one or more electrically-driven devices physically coupled to the second primary side of the base portion.

In at least one embodiment, the device may further include one or more integrated circuits embedded in the second primary side of the base portion or one or more electrically-driven devices physically coupled to the second primary side of the base portion. At least a first one of the one or more integrated circuits or the one or more electrically-driven devices may be on a first side of the slit opening. At least a second one of the one or more integrated circuits or the one or more electrically-driven devices may be on a second side of the slit opening opposite the first side of the slit opening. The slit opening may sever a direct-line thermal coupling path via conduction through the base portion between the first one of the one or more integrated circuits or the one or more electrically-driven devices and the second one of the one or more integrated circuits or the one or more electrically-driven devices.

In at least one embodiment, the silicon-based heat dissipation device may be made of single-crystal silicon.

In another aspect, a chip module assembly may include a chip module and a primary heat dissipation module. The chip module may include a board and at least one heat-generating device. The board may include a first primary side and a second primary side opposite the first primary side. The at least one heat-generating device may be disposed on the first primary side of the board. The primary heat dissipation module may include at least one silicon-based heat dissipation device disposed on the at least one heat-generating device.

In at least one embodiment, the at least one silicon-based heat dissipation device may be made of single-crystal silicon.

In at least one embodiment, the at least one silicon-based heat dissipation device may include a base portion and a protrusion portion. The base portion may include a first primary side and a second primary side opposite the first primary side. The protrusion portion may be on the first primary side of the base portion and protruding therefrom. The second primary side of the base portion may be in physical contact with the at least one heat-generating device such that at least a portion of heat generated by the at least one heat-generating device is dissipated to the silicon-based heat dissipation device by conduction.

In at least one embodiment, the base portion may include a slit opening that communicatively connects the first primary side and the second primary side of the base portion.

In at least one embodiment, the at least one heat-generating device may include a first heat-generating device and a second heat-generating device. The first heat-generating device may be on a first side of the slit opening and the second heat-generating device may be on a second side of the slit opening opposite the first side of the slit opening such that the slit opening severs a direct-line thermal coupling path via conduction through the base portion between the first and the second heat-generating devices.

In at least one embodiment, the slit opening may be an L-shaped slit opening.

In at least one embodiment, the protrusion portion of the silicon-based heat dissipation device may include a plurality of fins.

In at least one embodiment, the plurality of fins may include a plurality of pin fins.

In at least one embodiment, the plurality of fins may include a plurality of flared fins.

In at least one embodiment, the plurality of fins may include a plurality of straight fins.

In at least one embodiment, a ratio of a height of the fins, measured from the first primary side of the base portion in a direction perpendicular to the first primary side, to a thickness of each of the fins, measured across a respective one of the fins in a direction parallel to the first primary side of the base portion, may be greater than 5:1.

In at least one embodiment, a ratio of a height of the fins, measured from the first primary side of the base portion in a direction perpendicular to the first primary side, to a thickness of the base portion, measured across the base portion in a direction parallel to the first primary side of the base portion, may be greater than 5:1.

In at least one embodiment, a spacing between every two fins of the fins, measured between respective two fins of the fins in a direction parallel to the first primary side of the base portion, may be greater than or equal to a thickness of each of the fins, measured across a respective one of the fins in the direction parallel to the first primary side of the base portion.

In at least one embodiment, the at least one heat-generating device may include a plurality of heat-generating devices, and the at least one silicon-based heat dissipation device may include a plurality of silicon-based heat dissipation devices each of which disposed on one or more of the heat-generating devices.

In at least one embodiment, a first portion of the heat-generating devices may be disposed on the first primary side of the board and a second portion of the heat-generating devices may be disposed on the second primary side of the board. At least a first one of the silicon-based heat dissipation devices may be disposed on one or more of the heat-generating devices disposed on the first primary side of the board and at least a second one of the silicon-based heat dissipation devices may be disposed on one or more of the heat-generating devices disposed on the second primary side of the board.

In at least one embodiment, the heat-generating devices may include memory chips.

In at least one embodiment, the chip module assembly may further include a secondary heat dissipation module. The secondary heat dissipation module may include a first frame disposed on the first primary side of the board of the chip module. The first frame may include a louver and a plurality of posts. The louver may include at least an angled surface that directs an air flow toward the at least one silicon-based heat dissipation device. The first frame may be in physical contact with the board through the plurality of posts.

In at least one embodiment, the primary heat dissipation module and the secondary heat dissipation module may not be in physical contact with one another.

In at least one embodiment, the first frame may be made of a metallic material.

In at least one embodiment, the secondary heat dissipation module may further include a second frame disposed on the second primary side of the board of the chip module. The second frame may include a louver and a plurality of posts through which the second frame is in physical contact with the second primary side of the board. The louver may include at least an angled surface.

The proposed techniques are further described below in the detailed description. This summary is not intended to identify essential features of the claimed subject matter, nor is it intended for use in determining the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of the present disclosure. The drawings illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. It is appreciable that the drawings are not necessarily in scale as some components may be shown to be out of proportion than the size in actual implementation in order to clearly illustrate the concept of the present disclosure.

FIG. 1 is a partial cross-sectional view of a heat dissipation device in accordance with an embodiment of the present disclosure.

FIG. 2 is a partial cross-sectional view of a heat dissipation device in accordance with an embodiment of the present disclosure.

FIG. 3 is a partial cross-sectional view of a heat dissipation device in accordance with an embodiment of the present disclosure.

FIG. 4 is a perspective view of a heat dissipation device in accordance with an embodiment of the present disclosure.

FIG. 5 is a partial cross-sectional view of the heat dissipation device of FIG. 4.

FIG. 6 is a perspective top view of a device in accordance with an embodiment of the present disclosure.

FIG. 7 is a perspective bottom view of the device of FIG. 6.

FIG. 8 is a side view of the device of FIG. 6.

FIG. 9 is a perspective top view of a device in accordance with another embodiment of the present disclosure.

FIG. 10 is a perspective bottom view of the device of FIG. 9.

FIG. 11 is an exploded view of a chip module assembly utilizing heat dissipation devices in accordance with an embodiment of the present disclosure.

FIG. 12 is a first perspective view of the chip module assembly of FIG. 11.

FIG. 13 is a second perspective view of the chip module assembly of FIG. 11.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Overview

A compact heat sink or radiator built with silicon-based material provide a compact and highly efficient heat sink for all electronics applications such as driver circuits, microprocessors, graphics processors, memory chips, GPS chips, communications chips, laser diodes including edge-emitting lasers and VCSELs, LEDs, photodiodes, sensors, etc. One advantage of a silicon-based heat sink or radiator is that it can have a surface area more than ten times that of a typical metal-based heat sink or radiator which may be fabricated by extrusion, stamping or machining process. Besides, the surface quality of the silicon fins of a silicon-based heat sink or radiator can reach an optically polished quality surpassing the surface quality of conventional metal-based heat sinks and radiators. A silicon-based heat sink or radiator does not corrode or become tarnished in atmosphere due to elements of the environment. In contrast, metal-based heat sinks and radiators tend to foul and/or corrode over time. The aforementioned advantages enhance the reliability and thermal dissipation efficiency of silicon-based heat sinks and radiators.

Illustrative Implementations

Each of FIGS. 1-3 respectively illustrates a partial cross-sectional view of a silicon-based heat dissipation device in accordance with an embodiment of the present disclosure. FIG. 4 illustrates a silicon-based heat dissipation device 101 in accordance with an embodiment of the present disclosure. FIG. 5 illustrates dimensions associated with the silicon-based heat dissipation device of FIG. 4. The following description refers to FIGS. 1-5.

Each of FIGS. 1-3 illustrates a respective embodiment of a cross-sectional view of a fin structure of multiple straight fins of a silicon-based heat dissipation device 101. Due to efficient thermal performance and compact structure of the silicon-based heat dissipation device 101, a surface area at least ten times that of a typical metal-based heat sink or radiator to interact with air or air-sol cooling can be achieved.

The silicon-based heat dissipation device 101 shown in FIG. 4 can be fabricated from a piece of single-crystal silicon by etching various structural shapes as shown in FIGS. 1-3. As shown in FIG. 4, the silicon-based heat dissipation device 101 has a base portion 2 and a protrusion portion 1. The base portion 2 has a first primary side (e.g., the side that faces up in FIG. 4) and a second primary side (e.g., the side that faces down in FIG. 4) opposite the first primary side. The protrusion portion 1 of the silicon-based heat dissipation device 101 is on the first primary side of the base portion 2 and protrudes therefrom. In the example shown in FIG. 4, the protrusion portion 1 includes multiple straight fins. The multiple straight fins of the protrusion portion 1 may be spaced apart from each other by an equidistant spacing 11. Additionally or alternatively, the protrusion portion 1 may include pin fins and/or flared fins. In one embodiment, the silicon-based heat dissipation device 101 may be made from a single-crystal silicon wafer where multiple grooves are etched onto one side of the silicon wafer by etching, e.g., chemical etching, to form the multiple straight fins of the protrusion portion 1.

As shown in FIG. 5, there are several dimensions associated with the silicon-based heat dissipation device 101. T1 denotes a thickness of the base portion 2 that is measured across the base portion 2 in a direction parallel to the first primary side of the base portion 2. T2 denotes a height of the protrusion portion 1, or the fins of the protrusion portion 1, that is measured from the first primary side of the base portion 2 in a direction perpendicular to the first primary side of the base portion 2. T3 denotes a width of the spacing 11 between every two adjacent fins of the protrusion portion 1. T4 denotes a thickness of each of the fins of the protrusion portion 1, measured across a respective one of the fins in a direction parallel to the first primary side of the base portion 2.

In one embodiment, the ratio T2:T4 is a large number in order to increase the surface area of the silicon-based heat dissipation device 101 in a small footprint of silicon base. In order to achieve a high convective cooling in the silicon-based heat dissipation device 101, the ratio of T2:T4 is greater than 5:1. Similarly, the ratio T2:T1 is greater than 5:1. Moreover, in one embodiment, T3 is greater than or equal to T4. These dimensions and ratios provide an optimum performance of the silicon-based heat dissipation device 101. For example, if each of the dimensions T3 and T4 is 100 microns with T2 being 500 microns and T1 being 100 microns, then the silicon-based heat dissipation device 101 would have a large amount of surface area in a compact form factor. However, air flow through the spacing 11 between every two adjacent fins of the protrusion portion 1 may be restricted due to small gap, T3 to ineffectively remove all heat from silicon fin. To maximize thermal convection by air flow through the spacing 11 between every two adjacent fins of the protrusion portion 1, in various implementations the dimension T3 and air speed can be increased to achieve quick removal of heat from the fins of the silicon-based heat dissipation device 101.

FIGS. 6-8 illustrate a device 100 in accordance with an embodiment of the present disclosure. The following description refers to FIGS. 6-8.

FIG. 6 shows the device 100 which is a monolithic structure of IC chip or Silicon-On-Insulator (SOI) combined with the silicon-based heat dissipation device 101. Typically integrated circuits are developed or laid-down on a primary side of a silicon wafer, and then the backside of the silicon wafer opposite the primary side is lapped to make a thin silicon IC chip. In one embodiment, the silicon-based heat dissipation device 101 is built or attached to the backside of the IC or SOI chip to increase the heat dissipation by increasing the surface area of the existing backside of the IC or SOI structure. The silicon-based heat dissipation device 101 built on the backside of the IC or SOI chip provides more than ten times (10×) of surface area to dissipate heat from the integrated circuits by convection or forced air, compared to conventional metal-based heat sinks or radiators.

As shown in FIGS. 7 and 8, each of heat-generating devices 21-25 is embedded in or physically coupled, mounted or otherwise attached to the second primary side of the base portion 2, which is preferably flat and smooth to facilitate maximum contact, and thus thermal conduction, with the heat-generating devices 21-25. Each of heat-generating devices 23 and 25 may be an embedded or doped integrated circuit while each of heat-generating devices 21, 22 and 24 may be a driver chip, microprocessor, graphics processor, memory chip, GPS chip, communications chip, laser diode (edge-emitting or VCSEL), LED, photodiode, sensor or the like. Regardless what the case may be, each of heat-generating devices 21-25 generates heat when powered on for which heat needs to be removed to prolong the operational life and enhance the performance of the heat-generating devices 21-25. One of ordinary skill in the art would appreciate that, although multiple heat-generating devices are shown in FIGS. 7 and 8, in various embodiments the number of heat-generating devices may be more or less depending on the actual implementation.

FIGS. 9 and 10 illustrate a device 200 in accordance with another embodiment of the present disclosure. The following description refers to FIGS. 9 and 10.

The device 200 and the device 100 are similar in many ways. In the interest of brevity, detailed description of differences between the device 200 and the device 100 is provided herein while similarity therebetween is not repeated. As shown in FIGS. 9 and 10, the device 200 includes a silicon-based heat dissipation device 102 that has a base portion 6 and a protrusion portion 5. The base portion 6 has a first primary side and a second primary side opposite the first primary side. The protrusion portion 5 is on the first primary side of the base portion 6 and protrudes therefrom. The protrusion portion 5 may include multiple straight fins similar to those of the protrusion portion 1 of the silicon-based heat dissipation device 101. For example, the silicon-based heat dissipation device 102 may be made from a single-crystal silicon wafer where multiple grooves are etched onto one side of the silicon wafer by etching, e.g., chemical etching, to form the multiple straight fins of the protrusion portion 5.

The silicon-based heat dissipation device 102 includes a slit opening 12 on the base portion 6 that cuts off, or severs, a direct-line thermal coupling path via conduction through the base portion 6 between a first heat-generating device on one side of the slit opening 12 and a second heat-generating device on the other side of the slit opening 12. In one embodiment, the slit opening 12 may include an L-shaped slit opening as shown in FIGS. 9 and 10. Alternatively, the slit opening 12 may include a straight line or a zigzag line, depending on the actual implementation. In other embodiments, instead of a slit opening, the base portion 6 may include a trench or groove on either its first primary side or second primary side. Whether a slit opening, a groove or trench, such design would minimize thermal coupling by conduction between two or more heat-generating devices that are disposed on the heat dissipation device 102.

In the example shown in FIG. 10, each of heat-generating devices 26-29 is embedded in or physically coupled, mounted or otherwise attached to the second primary side of the base portion 6, which is preferably flat and smooth to facilitate maximum contact, and thus thermal conduction, with the heat-generating devices 26-29. As shown in FIG. 10, the heat-generating device 26 is on one side of the L-shaped slit opening 12 while the heat-generating devices 27, 28 and 29 are on the other side of the L-shaped slit opening 12. The slit opening 12 provides the function of severing a direct-line thermal coupling path (i.e., thermal conduction path) through the base portion 6 between the heat-generating device 26 and each of the heat-generating devices 27, 28 and 29. In this way, the absolute temperature of each of the heat-generating device 27, 28 and 29 can be lowered since they would not be heated by heat from the heat-generating device 26. This arrangement may be suitable, for example, when the heat-generating device 26 (e.g., a microprocessor) generates more heat than each of the heat-generating devices 27, 28 and 29 during operation. In one embodiment, the silicon-based heat dissipation device 102 may be fabricated on the backside of an IC or SOI chip.

FIGS. 11-13 illustrate an example application of heat dissipation devices of the present disclosure. In particular, FIGS. 11-13 illustrate an example chip cooling application in which a chip module assembly 5001 is equipped with a number of heat dissipation devices 101 and/or 102 in accordance with an embodiment of the present disclosure. The description below refers to FIGS. 11-13.

Chip module assembly 5001 may include a chip module 901 and a primary heat dissipation module. Chip module 901 may include a board 750 (e.g., a printed circuit board or PCB), a number of memory chips 701 and a serial presence detect (SPD) chip 702. In the example shown in FIGS. 11-13, chip module 901 has twenty (20) memory chips 701 with ten memory chips 701 disposed on one side of board 750 and the other ten memory chips 701 disposed on the other side of board 750. The SPD chip 702 is disposed one side of board 750, e.g., between five of the ten memory chips 701 on that side as shown in FIG. 11. Memory chips 701 may include, for example, SRAM (static random access memory), DRAM (dynamic random access memory), EEPROM (electrically erasable programmable read-only memory), flash memory, or any semiconductor memory device presently available or developed in the future. Those of ordinary skill in the art would appreciate that, although certain number of memory chips 701 are shown in the example illustrated in FIGS. 11-13, the number of memory chips 701 may vary in other embodiments.

The primary heat dissipation module may include silicon-based heat dissipation devices 401 a, 401 b, 401 c, 401 d, 402 a, 402 b, 402 c, 402 d and 403. Each of the silicon-based heat dissipation devices 401 a, 401 b, 401 c, 401 d, 402 a, 402 b, 402 c, 402 d and 403 may be similar to silicon-based heat dissipation device 101 or 102 as described above. Thus, in the interest of brevity, detailed description of silicon-based heat dissipation devices 401 a, 401 b, 401 c, 401 d, 402 a, 402 b, 402 c, 402 d and 403 is not provided to avoid redundancy. Those of ordinary skill in the art would appreciate that, although certain number of silicon-based heat dissipation devices are shown in the example illustrated in FIGS. 11-13, the number of silicon-based heat dissipation devices may vary in other embodiments.

Each of the silicon-based heat dissipation devices 401 a, 401 b, 401 c, 401 d, 402 a, 402 b, 402 c and 402 d may correspond to one or more of the memory chips 701, while the silicon-based heat dissipation device 403 may correspond to the SPD chip 702. That is, each of the silicon-based heat dissipation devices 401 a, 401 b, 401 c, 401 d, 402 a, 402 b, 402 c and 402 d may be disposed on or physically coupled, bonded, adhered, mounted or otherwise attached to one or more of the memory chips 701. In the example illustrated in FIGS. 11-13, each of silicon-based heat dissipation devices 401 a, 401 b, 401 c and 401 d corresponds to two of the memory chips 701 and is disposed on or physically coupled, bonded, adhered, mounted or otherwise attached to two of the memory chips 701. Likewise, each of silicon-based heat dissipation devices 402 a, 402 b, 402 c and 402 d corresponds to three of the memory chips 701 and is disposed on or physically coupled, bonded, adhered, mounted or otherwise attached to three of the memory chips 701. As shown in FIGS. 11-13, silicon-based heat dissipation device 403 corresponds to the SPD chip 702 and is disposed on or physically coupled, bonded, adhered, mounted or otherwise attached to the SPD chip 702. This is because, as the SPD chip 702 tends to produce more heat than a single one of the memory chips 701, the SPD chip 702 is cooled by its own silicon-based heat dissipation device 403 which is separate from, and thus thermally decoupled from, the other silicon-based heat dissipation devices 401 a, 401 b, 401 c, 401 d, 402 a, 402 b, 402 c and 402 d.

As each of the silicon-based heat dissipation devices 401 a, 401 b, 401 c, 401 d, 402 a, 402 b, 402 c and 402 d is disposed on or physically coupled, bonded, adhered, mounted or otherwise attached to more than one of the memory chips 701, in one embodiment, at least one of the silicon-based heat dissipation devices 401 a, 401 b, 401 c, 401 d, 402 a, 402 b, 402 c and 402 d may be similar to the silicon-based heat dissipation device 102 and include one or more slit openings. For example, when the respective silicon-based heat dissipation device corresponds to two of the memory chips 701, there may be one slit opening that serves to thermally decouple one half of the respective silicon-based heat dissipation device which corresponds to one of the two memory chips 701 and the other half of the respective silicon-based heat dissipation device which corresponds to the other one of the two memory chips 701. Similarly, when the respective silicon-based heat dissipation device corresponds to three of the memory chips 701, there may be two slit openings that serve to thermally decouple the three sections of the respective silicon-based heat dissipation device where each of the three sections of the respective silicon-based heat dissipation device corresponds to one of the three memory chips 701.

In one embodiment, at least one of the silicon-based heat dissipation devices 401 a, 401 b, 401 c, 401 d, 402 a, 402 b, 402 c, 402 d and 403 is solder bonded onto the molding compound of the respective memory chip(s) 701 or SPD chip 702. Alternatively, at least one of the silicon-based heat dissipation devices 401 a, 401 b, 401 c, 401 d, 402 a, 402 b, 402 c, 402 d and 403 is adhered to the respective memory chip(s) 701 or SPD chip 702 by thermally-conductive epoxy.

In other embodiments, the primary heat dissipation module may include more or fewer silicon-based heat dissipation devices than that illustrated in FIGS. 11-13. For example, each of the memory chips 701 may correspond to a respective one of the silicon-based heat dissipation devices. In other words, in one embodiment, each of the silicon-based heat dissipation devices would be disposed on or physically coupled, bonded, adhered, mounted or otherwise attached to a respective one of the memory chips 701. Alternatively, one silicon-based heat dissipation device may be provided on each side of board 750 such that the chips on a given side of board 750 are in contact with and thus cooled by the same silicon-based heat dissipation device.

As each of the silicon-based heat dissipation devices 401 a, 401 b, 401 c, 401 d, 402 a, 402 b, 402 c, 402 d and 403 is similar to the above-described silicon-based heat dissipation device 101 or 102, the base portion of each of the silicon-based heat dissipation devices 401 a, 401 b, 401 c, 401 d, 402 a, 402 b, 402 c, 402 d and 403 is disposed on or physically coupled, bonded, adhered, mounted or otherwise attached to the respective one or more memory chips 701 or the SPD chip 702. The protrusion portion of each of the silicon-based heat dissipation devices 401 a, 401 b, 401 c, 401 d, 402 a, 402 b, 402 c, 402 d and 403 is exposed to the ambience. Each of the silicon-based heat dissipation devices 401 a, 401 b, 401 c, 401 d, 402 a, 402 b, 402 c, 402 d and 403 is oriented such that the straight fins of the protrusion portion are aligned in the same direction.

For example, as shown in FIGS. 11-13, the straight fins of the protrusion portion of each of the silicon-based heat dissipation devices 401 a, 401 b, 401 c, 401 d, 402 a, 402 b, 402 c, 402 d and 403 is aligned with the longitudinal axis of the board 750 that traverses the board 750 from one distal end to the opposite distal end of the board 750. This allows a relatively smooth air flow to flow through the straight fins when, for example, one or more fans are provided on one distal end of the board 750 to provide the air flow. The relatively smooth air flow results in a laminar flow, as opposed to a turbulent flow, and thereby maximizes heat transfer or dissipation via convection from the silicon-based heat dissipation devices 401 a, 401 b, 401 c, 401 d, 402 a, 402 b, 402 c, 402 d and 403 to the air flow.

Chip module assembly 5001 may additionally include a secondary heat dissipation module. The secondary heat dissipation module may include either or both of a first frame 301 and a second frame 302. Each of the first and second frames 301 and 302 is disposed on a respective side of the board 750 over the primary heat dissipation module. For example, as shown in FIGS. 11-13, the first frame 301 is disposed on a first primary side of the board 750 over the silicon-based heat dissipation devices 401 a, 401 b, 402 a, 402 b and 403 and ten of the twenty memory chips 701 as well as the SPD chip 702. Correspondingly, as shown in FIGS. 11-13, the second frame 302 is disposed on a second primary side of the board 750 (that is opposite the first primary side of the board 750) over the silicon-based heat dissipation devices 401 c, 401 d, 402 c and 402 d and the remaining ten of the twenty memory chips 701. If the chip module assembly 5001 has memory chips on one but not both sides of the board 750, then the secondary heat dissipation module would include one but not both of the first and second frames 301 and 302.

Each of the first and second frames 301 and 302 may be made of a metallic material or a plastic material. For example, at least one of the first and second frames 301 and 302 may be made of aluminum or zinc. Each of the first and second frames 301 and 302 may be disposed on or physically coupled, bonded, mounted or otherwise attached to the board 750 by mechanical means (e.g., screws) or by any other suitable means. As the first and second frames 301 and 302 are similar or identical to one another, the following description of the first frame 301 equally applies to the second frame 302.

The first frame 301 may include a louver 303, and posts 304, 305, 306, 307, 308, 309 and 310 that protrude from the same side of the frame 301. The louver 303 may include one or more angled surfaces such that the louver 303 may function as an air flow defector to direct air flow toward the fins of the silicon-based heat dissipation devices 401 a, 401 b, 402 a, 402 b and 403.

Posts 304, 305, 306, 307, 308, 309 and 310 are strategically located on the first frame 301 such that, when the first frame 301 is disposed on or otherwise mounted to the board 750, posts 307, 308, 309 and 310 function as heat-sinking posts around the four corners on the first primary side of the board 750 while posts 304, 305 and 306 function as heat-sinking posts around and near the SPD chip 702. In other words, at least part of the heat generated by memory chips 701 and SPD chip 702 can be transferred to the first and second frames 301 and 302 by conduction through the board 750.

An additional function of each of the first and second frames 301 and 302 is to provide protection of the fins of the silicon-based heat dissipation devices 401 a, 401 b, 401 c, 401 d, 402 a, 402 b, 402 c, 402 d and 403 from damage caused by direct impact/contact with an external object.

The design of the primary heat dissipation module and the secondary heat dissipation module provides dual heat-transfer paths to dissipate heat from the chip module 901. The primary heat dissipation module (i.e., the silicon-based heat dissipation devices 401 a, 401 b, 401 c, 401 d, 402 a, 402 b, 402 c, 402 d and 403) is in direct contact with the memory chips 701 and SPD chip 702 and thus provides one heat-transfer path to dissipate heat from the chip module 901. The secondary heat dissipation module (i.e., the first and second frames 301 and 302) is in direct contact with the board 750 and thus provides another heat-transfer path to dissipate heat from the chip module 901. The primary heat dissipation module and the secondary heat dissipation module, however, are not in direction contact with one another and, therefore, are thermally isolated from one another.

Those of ordinary skill in the art would appreciate that, although the example illustrated in FIGS. 11-13 involves heat dissipation for memory chips of a memory chip module, embodiments and techniques of the novel and non-obvious design of the present disclosure may as well be applied to other applications in which the heat-generating devices are not memory chips. For instance, instead of memory chips, a design similar to that illustrated in FIGS. 11-13 may be used to cool a chip set that includes a microprocessor functioning as a central processing unit (CPU) and one or more other chips such as a graphics processor, one or more memory chips, a network communication chip and/or a wireless communication chip.

In summary, in one aspect of the present disclosure, a device may include a silicon-based heat dissipation device. The silicon-based heat dissipation device may include a base portion and a protrusion portion. The base portion may have a first primary side and a second primary side opposite the first primary side. The protrusion portion may be on the first primary side of the base portion and may protrude therefrom. The second primary side of the base portion may be configured to have one or more heat-generating devices embedded therein or physically coupled thereto such that at least a portion of heat generated by the one or more heat-generating devices is dissipated to the silicon-based heat dissipation device by conduction.

In at least one embodiment, the base portion may include a slit opening that communicatively connects the first primary side and the second primary side of the base portion.

In at least one embodiment, when each of more than one heat-generating devices is embedded in or physically coupled to the base portion, at least a first heat-generating device of the more than one heat-generating devices may be on a first side of the slit opening and at least a second heat-generating device of the more than one heat-generating devices may be on a second side of the slit opening opposite the first side of the slit opening such that the slit opening severs a direct-line thermal coupling path via conduction through the base portion between the first and the second heat-generating devices.

In at least one embodiment, the slit opening may include an L-shaped slit opening.

In at least one embodiment, the protrusion portion of the silicon-based heat dissipation device may include a plurality of fins.

In at least one embodiment, the plurality of fins may include a plurality of straight fins.

In at least one embodiment, a ratio of a height of the fins, measured from the first primary side of the base portion in a direction perpendicular to the first primary side, to a thickness of each of the fins, measured across a respective one of the fins in a direction parallel to the first primary side of the base portion, may be greater than 5:1.

In at least one embodiment, a ratio of a height of the fins, measured from the first primary side of the base portion in a direction perpendicular to the first primary side, to a thickness of the base portion, measured across the base portion in a direction parallel to the first primary side of the base portion, may be greater than 5:1.

In at least one embodiment, a spacing between every two fins of the fins, measured between respective two fins of the fins in a direction parallel to the first primary side of the base portion, may be greater than or equal to a thickness of each of the fins, measured across a respective one of the fins in the direction parallel to the first primary side of the base portion.

In at least one embodiment, the plurality of fins may include a plurality of pin fins.

In at least one embodiment, the plurality of fins may include a plurality of flared fins.

In at least one embodiment, the device may further include one or more integrated circuits embedded in the second primary side of the base portion or one or more electrically-driven devices physically coupled to the second primary side of the base portion.

In at least one embodiment, the device may further include one or more integrated circuits embedded in the second primary side of the base portion or one or more electrically-driven devices physically coupled to the second primary side of the base portion. At least a first one of the one or more integrated circuits or the one or more electrically-driven devices may be on a first side of the slit opening. At least a second one of the one or more integrated circuits or the one or more electrically-driven devices may be on a second side of the slit opening opposite the first side of the slit opening. The slit opening may sever a direct-line thermal coupling path via conduction through the base portion between the first one of the one or more integrated circuits or the one or more electrically-driven devices and the second one of the one or more integrated circuits or the one or more electrically-driven devices.

In at least one embodiment, the silicon-based heat dissipation device may be made of single-crystal silicon.

In another aspect, a chip module assembly may include a chip module and a primary heat dissipation module. The chip module may include a board and at least one heat-generating device. The board may include a first primary side and a second primary side opposite the first primary side. The at least one heat-generating device may be disposed on the first primary side of the board. The primary heat dissipation module may include at least one silicon-based heat dissipation device disposed on the at least one heat-generating device.

In at least one embodiment, the at least one silicon-based heat dissipation device may be made of single-crystal silicon.

In at least one embodiment, the at least one silicon-based heat dissipation device may include a base portion and a protrusion portion. The base portion may include a first primary side and a second primary side opposite the first primary side. The protrusion portion may be on the first primary side of the base portion and protruding therefrom. The second primary side of the base portion may be in physical contact with the at least one heat-generating device such that at least a portion of heat generated by the at least one heat-generating device is dissipated to the silicon-based heat dissipation device by conduction.

In at least one embodiment, the base portion may include a slit opening that communicatively connects the first primary side and the second primary side of the base portion.

In at least one embodiment, the at least one heat-generating device may include a first heat-generating device and a second heat-generating device. The first heat-generating device may be on a first side of the slit opening and the second heat-generating device may be on a second side of the slit opening opposite the first side of the slit opening such that the slit opening severs a direct-line thermal coupling path via conduction through the base portion between the first and the second heat-generating devices.

In at least one embodiment, the slit opening may be an L-shaped slit opening.

In at least one embodiment, the protrusion portion of the silicon-based heat dissipation device may include a plurality of fins.

In at least one embodiment, the plurality of fins may include a plurality of pin fins.

In at least one embodiment, the plurality of fins may include a plurality of flared fins.

In at least one embodiment, the plurality of fins may include a plurality of straight fins.

In at least one embodiment, a ratio of a height of the fins, measured from the first primary side of the base portion in a direction perpendicular to the first primary side, to a thickness of each of the fins, measured across a respective one of the fins in a direction parallel to the first primary side of the base portion, may be greater than 5:1.

In at least one embodiment, a ratio of a height of the fins, measured from the first primary side of the base portion in a direction perpendicular to the first primary side, to a thickness of the base portion, measured across the base portion in a direction parallel to the first primary side of the base portion, may be greater than 5:1.

In at least one embodiment, a spacing between every two fins of the fins, measured between respective two fins of the fins in a direction parallel to the first primary side of the base portion, may be greater than or equal to a thickness of each of the fins, measured across a respective one of the fins in the direction parallel to the first primary side of the base portion.

In at least one embodiment, the at least one heat-generating device may include a plurality of heat-generating devices, and the at least one silicon-based heat dissipation device may include a plurality of silicon-based heat dissipation devices each of which disposed on one or more of the heat-generating devices.

In at least one embodiment, a first portion of the heat-generating devices may be disposed on the first primary side of the board and a second portion of the heat-generating devices may be disposed on the second primary side of the board. At least a first one of the silicon-based heat dissipation devices may be disposed on one or more of the heat-generating devices disposed on the first primary side of the board and at least a second one of the silicon-based heat dissipation devices may be disposed on one or more of the heat-generating devices disposed on the second primary side of the board.

In at least one embodiment, the heat-generating devices may include memory chips.

In at least one embodiment, the chip module assembly may further include a secondary heat dissipation module. The secondary heat dissipation module may include a first frame disposed on the first primary side of the board of the chip module. The first frame may include a louver and a plurality of posts. The louver may include at least an angled surface that directs an air flow toward the at least one silicon-based heat dissipation device. The first frame may be in physical contact with the board through the plurality of posts.

In at least one embodiment, the primary heat dissipation module and the secondary heat dissipation module may not be in physical contact with one another.

In at least one embodiment, the first frame may be made of a metallic material.

In at least one embodiment, the secondary heat dissipation module may further include a second frame disposed on the second primary side of the board of the chip module. The second frame may include a louver and a plurality of posts through which the second frame is in physical contact with the second primary side of the board. The louver may include at least an angled surface.

Additional and Alternative Implementation Notes

The above-described embodiments pertain to a technique, design, scheme, device and mechanism for isolation of thermal ground for multiple heat-generating devices on a substrate. Although the embodiments have been described in language specific to certain applications, it is to be understood that the appended claims are not necessarily limited to the specific features or applications described herein. Rather, the specific features and applications are disclosed as example forms of implementing such techniques.

In the above description of example implementations, for purposes of explanation, specific numbers, materials configurations, and other details are set forth in order to better explain the invention, as claimed. However, it will be apparent to one skilled in the art that the claimed invention may be practiced using different details than the example ones described herein. In other instances, well-known features are omitted or simplified to clarify the description of the example implementations.

The described embodiments are intended to be primarily examples. The described embodiments are not meant to limit the scope of the appended claims. Rather, the claimed invention might also be embodied and implemented in other ways, in conjunction with other present or future technologies.

Moreover, the word “example” is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “example” is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the word example is intended to present concepts and techniques in a concrete fashion. The term “techniques,” for instance, may refer to one or more devices, apparatuses, systems, methods, articles of manufacture, and/or computer-readable instructions as indicated by the context described herein.

As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless specified otherwise or clear from context, “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then “X employs A or B” is satisfied under any of the foregoing instances. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more,” unless specified otherwise or clear from context to be directed to a singular form. 

What is claimed is:
 1. A chip module assembly, comprising: a chip module, comprising: a board having a first primary side and a second primary side opposite the first primary side; and at least one heat-generating device disposed on the first primary side of the board; a primary heat dissipation module, comprising: at least one silicon-based heat dissipation device disposed on the first primary side of the board, the at least one silicon-based heat dissipation device on the at least one heat-generating device; and a secondary heat dissipation module comprising a first frame disposed on the first primary side of the board, the first frame comprising: a plurality of first louvers each having at least an angled surface that directs an air flow toward the at least one silicon-based heat dissipation device, each of the first louvers adjacent to a respective side of at least one respective silicon-based heat dissipation device of the at least one silicon-based heat dissipation device; and a plurality of first posts through which the first frame is in physical contact with the board, each of the first posts contacting a peripheral portion of the board.
 2. The chip module assembly of claim 1, wherein the at least one silicon-based heat dissipation device is made of single-crystal silicon.
 3. The chip module assembly of claim 1, wherein the at least one silicon-based heat dissipation device comprises: a base portion having a first primary side and a second primary side opposite the first primary side; and a protrusion portion on the first primary side of the base portion and protruding therefrom, wherein the second primary side of the base portion is in physical contact with the at least one heat-generating device such that at least a portion of heat generated by the at least one heat-generating device is dissipated to the at least one silicon-based heat dissipation device by conduction.
 4. The chip module assembly of claim 3, wherein the base portion comprises a slit opening that communicatively connects the first primary side and the second primary side of the base portion.
 5. The chip module assembly of claim 4, wherein the at least one heat-generating device comprises a first heat-generating device and a second heat-generating device, and wherein the first heat-generating device is on a first side of the slit opening and the second heat-generating device is on a second side of the slit opening opposite the first side of the slit opening such that the slit opening severs a direct-line thermal coupling path via conduction through the base portion between the first heat-generating device and the second heat-generating device.
 6. The chip module assembly of claim 4, wherein the slit opening comprises an L-shaped slit opening.
 7. The chip module assembly of claim 3, wherein the protrusion portion of the silicon-based heat dissipation device comprises a plurality of fins.
 8. The chip module assembly of claim 7, wherein the plurality of fins comprises a plurality of pin fins.
 9. The chip module assembly of claim 7, wherein the plurality of fins comprises a plurality of flared fins.
 10. The chip module assembly of claim 7, wherein the plurality of fins comprises a plurality of straight fins.
 11. The chip module assembly of claim 10, wherein a ratio of a height of the straight fins, measured from the first primary side of the base portion in a direction perpendicular to the first primary side, to a thickness of each of the straight fins, measured across a respective one of the straight fins in a direction parallel to the first primary side of the base portion, is greater than 5:1.
 12. The chip module assembly of claim 10, wherein a ratio of a height of the straight fins, measured from the first primary side of the base portion in a direction perpendicular to the first primary side, to a thickness of the base portion, measured across the base portion in a direction parallel to the first primary side of the base portion, is greater than 5:1.
 13. The chip module assembly of claim 10, wherein a spacing between every two straight fins of the fins, measured between respective two straight fins of the straight fins in a direction parallel to the first primary side of the base portion, is greater than or equal to a thickness of each of the straight fins, measured across a respective one of the straight fins in the direction parallel to the first primary side of the base portion.
 14. The chip module assembly of claim 1, wherein the at least one heat-generating device comprises a plurality of heat-generating devices, and wherein the at least one silicon-based heat dissipation device comprises a plurality of silicon-based heat dissipation devices each of which disposed on one or more of the plurality of heat-generating devices.
 15. The chip module assembly of claim 14, wherein a first portion of the at least one heat-generating devices is disposed on the first primary side of the board and a second portion of the at least one heat-generating devices is disposed on the second primary side of the board, and wherein at least a first one of the at least one silicon-based heat dissipation device is disposed on a first one or more of the at least one heat-generating devices disposed on the first primary side of the board and at least a second one of the at least one silicon-based heat dissipation device is disposed on a second one or more of the at least one heat-generating device disposed on the second primary side of the board.
 16. The chip module assembly of claim 14, wherein the at least one heat-generating device comprises memory chips.
 17. The chip module assembly of claim 1, wherein the primary heat dissipation module and the secondary heat dissipation module are not in physical contact with one another.
 18. The chip module assembly of claim 1, wherein the first frame is made of a metallic material.
 19. The chip module assembly of claim 1, wherein a first portion of the at least one heat-generating devices is disposed on the first primary side of the board and a second portion of the at least one heat-generating devices is disposed on the second primary side of the board, and wherein the secondary heat dissipation module further comprises a second frame disposed on the second primary side of the board of the chip module, the second frame comprising: a plurality of second louvers each having at least an angled surface that directs an air flow toward the second portion of the at least one silicon-based heat dissipation device, each of the second louvers adjacent to a respective side of at least one respective silicon-based heat dissipation device of the at least one silicon-based heat dissipation device on the second primary side of the board; and a plurality of second posts through which the second frame is in physical contact with the board, each of the second posts contacting the peripheral portion of the board. 